WASHINGTON - The push to end the ban on gays openly serving in the U.S. military is gaining steam, even though Republicans have pledged to put the brakes on a proposed repeal of the so-called "Don't Ask, Don't Tell" law in the weeks to come.

Gay rights activists showed up Monday at the office of Harry Reid, the Senate majority leader, to push him to move forward with a repeal of the controversial ban. The group was lead by Daniel Choi, an Iraq war veteran discharged from the military under "Don't Ask, Don't Tell."

The protesters later chained themselves to a fence outside the White House. Thirteen people, including Choi and several other former U.S. soldiers, were arrested.

Prominent Republicans, in particular Arizona Sen. John McCain, say it's unlikely the ban will be overturned in the upcoming session of Congress, dubbed a lame-duck session since many of the lawmakers present lost their bids for re-election and will be gone in January.

Republicans are digging in their heels despite top military officials pushing for a repeal and polls that suggest an overwhelming majority of Americans want the ban overturned.

An upcoming Pentagon report, leaked to the Washington Post, suggests that 70 per cent of military personnel advocate doing away with the ban. The study also found that repealing it would have little or no impact on military operations.

"In the classic situation when you're in battle, you don't care what anybody's sexual orientation or race or gender or nationality or religion is," Joe Lieberman, an independent senator from Connecticut who's been avidly pushing for a repeal, said in an interview Monday on MSNBC.

"You care about whether they're going to fight well, and that's the way it ought to be."

U.S. President Barack Obama has said a repeal is possible in December or early January, after the Pentagon officially tables its report on Dec. 1. Defence Secretary Bill Gates has also urged a legislative overturn; so has Mike Mullen, chairman of the joint chiefs of staff.

Lieberman expressed optimism Monday that overturning the ban was still possible in the weeks to come.

"I'm not giving up on us doing a repeal of 'Don't Ask, Don't Tell' during the lame-duck session," he said. "We've got time to do this, and it's the right thing to do."

But others, including Gates, have suggested the prospects for such a repeal are dim when the 112th Congress begins in January. Republicans will take control of the House of Representatives and Democrats will have a far narrower majority in the U.S. Senate.

This week, one of the military officers who authored the Pentagon study is scheduled to testify before the Senate Armed Services Committee. Gen. Carter Ham is expected to be quizzed on his report by senators.

His findings stand in stark contrast to McCain's claims in recent days. In weekend interviews, the Arizona senator, a former prison of war in Vietnam, said he's spoken to military personnel who have expressed concerns about the repeal.

That's a stance that's drawn intense criticism, both on the editorial pages of his home state, on Capitol Hill -- "I disagree strongly with my friend," Lieberman said Monday -- and, apparently, in the privacy of his own home. Meghan McCain, the daughter of the Arizona senator, has long advocated a repeal.

And now, the senator's wife Cindy has taken part in the popular "It Gets Better" campaign, aimed at helping gay, lesbian, bisexual and transgendered teens endure the persistent torment of bullying.

"Our political and religious leaders tell LGBT youth that they have no future.... They can't serve our country openly," she says in a video that went public last week.

"Our government treats the LGBT community as second-class citizens, why shouldn't (bullies)?"

By Friday, however, McCain's wife had partially backtracked, stating via her Twitter stream: "I fully support the ('It Gets Better') campaign and all it stands for and am proud to be a part of it. But I stand by my husband's stance on ('Don't Ask, Don't Tell')."

McCain has said he'll want hearings into the findings of the Pentagon report, further diminishing any suggestion that the repeal could be quickly pushed through the Senate. His anti-repeal position comes amid reports that conservative leaders want Republican legislators to leave social issues alone and focus on shrinking government in the months to come.

Reid is scheduled to meet with Republican Mitch McConnell, the Senate minority leader, later this week to discuss what's on the legislative agenda in the coming weeks before lawmakers adjourn for the year.

The Democratic veteran is in a precarious position. The repeal is attached to the so-called defence authorization bill that has to be passed soon because it provides funding for the Pentagon and the military missions in Iraq and Afghanistan.

If Reid leaves the repeal in the bill, it likely won't pass before lawmakers adjourn. If he removes it, Obama's liberal base will be infuriated.

Legislators historically don't like to hold up the defence bill's passage, fearing it will cause them to be viewed as anti-military.

On Friday, the U.S. Supreme Court decided against stopping enforcement of "Don't Ask, Don't Tell" while its constitutionality is under review in the lower courts. Justice Elena Kagan has also recused herself from the case, raising the likelihood of a 4-4 tie should the issue ever appear before the court.

Kagan has been critical of the ban and helped come up with the Obama administration's response to it when she was solicitor general.

Photos

U.S. Defence Secretary Robert Gates speaks during a news conference at the Pentagon in this Aug. 9, 2010 file photo. (AP / Manuel Balce Ceneta)